In mixing faucets which receive and mix hot and cold water the discharge of the mixed water from the cartridge of the mixing faucet takes place either laterally through openings in the shell of the cartridge or through the bottom of the cartridge where the cold and hot water inlets are also located. In cartridges of the first type the mixed water fills the cartridge while in cartridges of the second type the water from the inlets in the bottom of the cartridge, after having been mixed, is routed to an outlet at the bottom of the cartridge without filling the cartridge itself. Therefore, the second type of cartridge does not include retention means between the interior of the cartridge itself and the control mechanisms that protrude toward the outside and does not require that the shell itself be water-tight.
Cartridges of the second type may also be used in faucets which receive only cold water, pipe it in regulated fractions to an outlet and to a passageway that conducts it to a low-pressure heating tank where a corresponding volume of hot water is displaced and is piped to the same outlet for cold water where it is mixed with the cold water coming from the faucet.
Cartridges of the type now under consideration using valve plates made of hard material contain an inherent problem. If the cartridge is installed in a mixing faucet, and if the mixed water coming out of the cartridge encounters appreciable resistance to flow, e.g., if it is piped across an aerator, then the resulting counterpressure acts on the mobile plate of the hard-material valve plate system tending to separate it from the fixed plate. If the mobile plate is separated from the fixed plate water fills the cartridge and, since the cartridge is not designed to exert a sealing force on the operating members, is diverted to the outside of the faucet. This phenomenon becomes particularly serious in cartridges of the so called "hydraulic-effect cartridges" where the pressure applied between the cooperating plates of the cartridge is a function of the water supply pressure.
When cartridges of this type are installed in a faucet that cooperates with a low-pressure hot-water tank the passage through which the cold water supply flows into the cartridge is at the high pressure end of the water pipeline and the above-mentioned deficiency becomes quite serious.
In cartridges of this type it is therefore usually necessary to preset between the plates of the cartridges a reciprocal pressure high enough to make impossible any separation, which--depending on the type of faucet in which the cartridge is installed--is due to the tapping counterpressure or the water supply pressure. This high pressure between the plates of the cartridge, however, is a serious inconvenience since operation of the faucet requires greater effort to the detriment of the user's comfort and entails major wear and tear of the parts to the detriment of the cartridges's service life.
A main purpose of this invention is to provide a cartridge that uses valve plates made of hard material intended for a faucet of the type where both the water inlets and outlets are located on the bottom of the cartridge and which does not have the above-mentioned deficiencies.
Another purposes of the invention is to provide a cartridge that has the desired features without appreciably increasing the cost of producing the cartridge.
Another purpose of the invention is to provide a cartridge that has the desired features and that can be made with dimensions and arrangements corresponding to those of conventional cartridges so as to insure interchangeability therewith.
These purposes are attained, in accordance with the invention, by virtue of the fact that the cartridge has a water-tight shell, that there are sealing means interposed between the interior of the cartridge and the operating members which are intended to protrude outside the faucet, and that there are provided means of communication which link the interior of the cartridge to a passage constituting the outlet for mixed water or the inlet for water which is to be mixed.
Due to the presence of means of communication between the interior of the cartridge and a passage constituting the outlet for mixed water or the inlet for water to be mixed, the pressure that is established in the interior of the cartridge is identical to the pressure prevailing in said passage, be said pressure very low such as when the cartridge is installed in a mixing faucet and water outflow takes place without encountering any appreciable resistance, or when in said installation a very high counterpressure is developed upon water outflow, or when the cartridge is installed in a faucet which cooperates with a low-pressure heater. Consequently, equal pressure is applied in every direction upon the mobile plate and the pressure that is established in said passage for water outlet or water supply does not in any harmful way alter the reciprocal pressure established between the mobile plate and the fixed plate of the cartridge. This reciprocal pressure can be determined by elastic means or by means that are sensitive to the pressure resulting from the intake of water or, preferably, both of these means; but in any case, this would substantially result independently of the pressure established in said water outlet or water supply passage. The correct operation of the cartridge thus is independent of the counter pressure upon outlet or the water supply pressure, and in no case can such a pressure cause the mobile plate to be moved away from the fixed plate.
The fact that the interior of the cartridge is full of water, possibly under a certain pressure, does not produce any problems. The shell of the cartridge is water-tight so that no loss of water occurs and the sealing means are arranged between the interior of the cartridge, which is full of water, and the operating mechanisms that communicate with the outside environment so that there cannot be any water loss.
A cartridge with these features therefore attains the main purpose of the invention. On the other hand, the particular construction of this cartridge does not appreciably change the manufacturing cost since no expensive parts are added, nor is there any need for any major assembly operations. Furthermore, the cartridge may readily be made to standard shapes and dimension and is therefore interchangeable with the customarily available cartridges.